Rubble Walls

Rubble walls are linear piles or semi-stacked assemblies of stone, often in an informal or irregular setting and shape. Stones will often be, or appear to be, found in the nearby landscape, and the wall itself may be composed of a variety of types and colors of stone. While this approach to wall construction carries the risk of appearing unorganized or chaotic, an artistic eye for mixing, matching, and arranging stones can turn visual variety into artwork.

Purpose/Uses

Rubble walls, can be useful for loosely defining the edge of a space without assuming too “architectural” an appearance. For instance, many New England (US) regional landscapes are bordered by walls that, if they weren’t initially, have become rubble walls due to lack of maintenance – these were originally made when early settlers attempting to farm their land redistributed found rocks and stones to the borders of their properties. Similarly, rubble walls can be used to incorporate found stones into a designed landscape (or to repurpose rock found while regrading a site to avoid having to cart it away).

As a rubble wall is essentially piled, loosely organized stone, it will tend to be a very stable structure and require little if any maintenance other than occasional weeding. The limiting factor in the lifespan of a rubble wall is the stability of the soil underneath and its potential to be eroded or shifted by other site conditions. Also, if softer stone (i.e. shale or loose sedimentary rock) is used, it may not hold up well to physical weathering or recreational uses (like hikers).

Construction

Base Preparation

The ground where the rubble wall will be build may or may not need to be prepared, depending on the particular way in which it will be constructed. In general, the larger or more substantial the wall will be, the more important it will be to properly compact your subgrade to be sure the ground will not subside or shift beneath the weight of the stone. It is commonly recommended that 6” of earth be excavated out, and an equal amount of crushed stone and/or sand be added and compacted to be sure of a stable base.

Placing Stones

This step will involve considerable variability, depending on what exactly is being constructed and the artistic eye of the designer. It is perhaps most helpful to seek out and review images of different types of “rubble wall” construction to develop a clear idea of exactly what the goal looks like. A few general guidelines:

• Sort through the available stone to find a selection of stones with natural right-angles or square ends, and flat faces; these can be used at the ends of the wall, or at any other point in the wall where a flatter face geometry is desired.
• Set up smaller or less visually appealing stones inside the wall, using them for support and to keep the ones that present well to the exterior.
• Keep in mind that in all mortar-free stone construction, gravity and static friction are going to be what holds the wall together. Evaluate what is being built periodically during construction – does it appear stable? Are any aspects of this construction hazardous, or are stones likely to fall off? If there are any trails or pathways crossing through the wall, it is best to be sure that any crossing points have stable stones as footings (since these walls are commonly found in natural or wooded sites which may contain walking trails).

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